The primary aims of my research are to contribute to our understanding of the ecology, evolution, and conservation of tropical vertebrate populations and their habitats. My published work encompasses anthropology, ecology, botany, conservation biology, and animal behavior. Below I highlight the main topics that my students, collaborators, and I have been working on recently. Click “Pubs” for a list of representative publications for each topic; pdfs of all papers are available under the “Publications” tab.

1. Gibbon and leaf monkey population ecology

Much of my published work is based on fieldwork on gibbons and leaf monkeys at the Cabang Panti Research Station in Gunung Palung, where I have worked since 1996. This site is remarkable in that it encompasses seven very different tropical forest types, permitting examination of the effects of key ecological variables while effectively controlling for many other, potentially confounding variables. This study system has revealed interesting patterns that increase our understanding of how habitat quality influences variables such as group size, population density, offspring sex ratio, and individual reproductive success, and indicates how these patterns vary among sexes, species, and in relation to diet and life history.  Pubs

2.  Vertebrate community ecology

Community ecologists have hotly debated the extent to which communities of organisms (i.e., all those inhabiting the same place at the same time) are structured by the distribution and abundance of resources, as opposed to being simply random assemblages of species. Virtually all primate ecologists, and many ecologists studying other vertebrates, assume that the species composition of communities is largely determined by the nature of available resources and the way in which these resources are partitioned among community members. This assumption has not, however, been carefully examined for primates (or indeed most vertebrates). Work I have been conducting over the past several years with Dr. Lydia Beaudrot shows that dispersal limitation, an essentially random process, plays a more important role in the assembly of primate communities than is typically assumed. Our ongoing work continues to address a critical gap in our understanding of primate community structure by investigating patterns of broader vertebrate communities at regional and local scales to understand the extent to which competition within and between taxonomic groups may structure these communities. Pubs

3. Orangutan conservation science

Orangutans are among the most iconic species in wildlife conservation. Most orangutan populations are severely threatened by habitat loss and illegal killing. Despite five decades of conservation attention, there has been frustratingly little progress and most wild populations will disappear over the next few decades unless threats are abated. Old models are clearly not effectively protecting orangutans, and innovative new concepts are required to ensure long-term persistence of this species. In collaboration with a number of fellow researchers, I have been studying new ways in which orangutan conservation might be more effective in the future. We see potential in new approaches that acknowledge the conservation value of degraded lands, take a broad, landscape-level approach to land-use planning, and address in creative ways the often competing needs of orangutans and economically-disadvantaged people. We are also convinced that success will require work with a wide range of stakeholders, including several entities– such as extractive industries (e.g., mining, forestry) and oil palm companies involved in wholesale land conversion– that conservationists typically view as adversaries. Pubs

4. Conservation biology of other vertebrates

Although the bulk of my conservation science has been in the context of orangutans in Indonesia, I have worked with a range of collaborators on projects that address both theoretical and applied questions relevant to the conservation biology of a range of other vertebrate taxa and in other regions. Recent topics that we have considered include road building in the tropics, correlates of sensitivity to selective logging, apparent competition and extinction risk in endangered ungulate prey, and effects of climate policy on biodiversity conservation. Pubs

5. Tropical forest phenology

Temporal patterns of plant growth and reproduction have important consequences for vertebrate populations that feed on plant fruits and leaves. Community-wide patterns (e.g., mast fruiting events) also have important implications for plant reproductive strategies. My team and I track the reproductive behavior of more than 6,000 plants across the gradient of forest types at our research site and use these data to examine how plant phenology affects vertebrate populations and plant community ecology. Pubs

6. Fallback foods

Physical anthropologists use the term “fallback foods” to denote resources of relatively poor nutritional quality that become particularly important dietary components during periods when preferred foods are scarce. Fallback foods are becoming increasingly invoked as key selective forces that determine masticatory and digestive anatomy, influence grouping and ranging behavior, and underlie fundamental evolutionary processes such as speciation, extinction, and adaptation. I am one of a number of primatologists and physical anthropologists actively conducting research on this topic. This work demonstrates that the consideration of fallback foods as a distinct class of food resource is warranted and may shed new light on our understanding of hominid feeding adaptations, with implications for a range of other topics. Pubs